1. Field of the Invention
The present invention relates to a system for connecting two substantially tubular members, more particularly two ferrules of an axial compressor case.
2. Description of the Related Art
Axial compressors, for example, in turbojets, are generally made with an axial sequence of rotors and stators. Each rotor is a set of rotary blades secured to the driving shaft of the compressor. Each stator is a set of stationary rectifying vanes secured to the compressor case. Each rotor is followed by a stator, so as to form a compressor stage.
A turbojet can comprise a plurality of successive compressors, for example, a low pressure compressor mounted in front of a high pressure compressor, where each comprises a different driving shaft.
Generally, an axial compressor case is formed with a set of substantially tubular members, also called ferrules, being successively connected. Each ferrule generally surrounds a compressor stage, i.e. a rotor and a stator. A ferrule will thus normally comprise the set of stationary vanes forming the stator, or means for securing said stationary vanes, as well as an abradable inner surface so as to avoid an excessive friction with the rotor blades.
The pairs of successive ferrules are connected via connecting systems comprising:                a) two flanges, each being substantially annular and comprising a proximal face adapted to be integral with one of the two successive ferrules and a distal face, and        b) securing members for clamping the distal faces of the two flanges one against the other, so as to be able to transmit tensile and compression axial stresses between both flanges assembled through clamping.        
As used herein, distal face means the most remote face of the ferrule body, whereas proximal face means the nearest one of the ferrule body. In the state of the art, there are used as securing members bolts crossing holes arranged in the flanges. However, such an arrangement has several inconvenients.
Should one of the compressor blades or vanes breaks, significant circumferential stresses will become added to the axial and radial stresses between the pairs of adjacent ferrules. Such stresses have a shearing effect on the bolts of the connecting system, requiring the use of a great number of bolts of a considerable diameter for securing ferrules. With the aim to solve the problem of the too numerous bolts, it is necessary to oversize the flanges by increasing the external diameter.
In addition to the cost and weight inconveniences resulting from such an oversizing, the radial bulk of enlarged flanges also shows other problems. So, in many applications, such bulk makes the assembling and disassembling operations difficult, because of interferences between flanges and members outside the compressor, such as, for example, hoods. More particularly, in the field of turbojets, it could be desirable to be able to disassemble the low pressure compressor at the rear in order to make the maintenance easier. However, if the connecting flanges for the ferrules of the low pressure compressor case are too bulky, they will abut against the intermediate case generally located at the back of the low pressure compressor and used for supporting the whole turbojet.